Rheostat construction



` Patented Sept.` 25,y 1928,.

PATENT joFFica DAVDWALD, or NEW YORK, N. Y.

Y RHEos'rAr coNs'rRuC'rroN.

Appiiatign fiieaaprii so, i925. 'seriai No..2s,s74.

',lhis invention relates to new and useful improvements in rlieostat construction, and more y particularly to rlieostatic devices'designed to be employediii radio receiving apparatus.

One of the objects ofthe invention is to Vprovide. new and improved means for ad`` justably mounting acontact arm upon lits operating shaft.

' Another object oflthe invention isto pro- 0 vide new and improved mounting for lthe contact armuponits shaft, whereby a nicer adjustment mayy be had than it has been possible to secure in devices of this character as hitherto constructed.y Y

Ruiother object of the invention isto yprovide means for clamping the operatingarm toits shaft, whereby the latter will not be indented or otherwise mutilated by the clamping mechanism.

A still vfurther object of the invention is to yprovide ina rlieostat of thefabove type means whereby a relative adjustment between the contact arin andthe operatingknob of the rheostat may -befreadily effected.

Other objects and aims of they invention,

more ork less speciiethan those referred tol above` will be in part obvious and in part pointed out in the course of the following description of the elements,combinations, arrangement of parts' and yapplicationof principles, Aconstituting the invention andthe s scope of protection contemplated will beindicated in the vappended claims.

`.In the accompanying drawings, "wherein I have illustrated ay preferredform of embodiment of my invention: l y f -Figure 1 is an elevationalv-iew of a panel` showing my improved rheostat i'mounted thereon. y l f V i i f Figurey 2 is' a rear elevational view Vof my improved rheostat. v l y i Figure 3 is a 'vertical sectional view taken substantially on the` lines 3-3 of Figure 2.

, Figure 4 is an elevational view of the conl tact ari'i'i; and

4 Figure 5 isfa cross-sectionalview taken through the rheostat showing a 4slightly moditied :form ofconstruction.` d Y v 'i Referring now tothe drawings, `wherein mi similar reference characters .ref-er tol similar parts throughout the several views thereof, l i the reference numeral 1 i of a radio set, upon whichy the rheostaticdevice is mounted. 2indicates a circular block of insulating material, which is adapted to be fastened to the panel 1 in any desired `portions 14 or l e uut 21 is locked in this desired adjusted p odenotes a panel boardmanner, yfor instance as by means of clamp'- ing screws 3, which pass through the block and enter thepanel. Block 2 carries theresistance unit 4, which is of the usual cir cular construction, so that the resistance wire may be engaged by the contact point- 5 of the Contact arm 6. One end of the resistance unit is connected with the binding post 7.`

Extending through an aperture 8in the block 2,` and adapted to rotate therein, is ay metallic sleeve 9, said sleeve being connect-ed witli'the binding post 1() by means ofthe plate 11. This sleeve has a head 12, which f passes through an aperture in said plate, so

that said sleeve is mechanically, as wellk as, electrically connected with the plate 11, and thereby with the binding at its outer end is threaded as at 13, and is provided with two flattened portions 14 and 15, the metal at these points being quite' thin. for a purpose which will be understood hereinafter.

The contact varm 6 is provided with an aperture 16, through whichthe outer threaded end of the sleeve 9 passes, the walls of the aperture having the straight portions 17 and 18, as shown, which are adapted to engage with the straight portions 14 and 15 respectively, of the sleeve, whereby said contact arm and said sleeve are non-rotatably connected.

Extending through the sleeve 9 is the operating shaft 19 of the device, said operating shaft being provided at its outer end with the operating knob or handle 20. Shaft 1'9 extends completely through the sleeve, as clearly shown in Figure the outer end of the sleeve 9 isa nutr 21, which nut, aswill be seen,clamps.the contact arm 6 againsta circular shoulder 22 formed on the insulating block 2, thereby holding the various movable parts ofthe device above described in assembled condition. The nut 21 is lprovided with a yscrew threaded laterally extending aperture 23, through which eX tendsV the clamping screw 24. Y

The inner end of vthis clamping crew is adapted to engage with either of the flattened 15 of the sleeve 9,*whereby`the screw threaded end of said screw 24, extendingas it does through thenut 21, may be adjusted to distort the metal comprising either of the flattened portions 14 or 1,5 of the sleeve, where? by the ,sleeve will be caused gage with'the operating shaft, so that the sition upon the sleeve. The clamping post 10. Sleeve 9,

tightly to en-v 2. Threaded upon A associated parts will be locked or held frictionally against relative rotative movement.

Atthis point it may be noted that heretofore. in the construction of rheostatic devices of this character it has been customary to employ a set screw which directly engages the operating shaft. Frequent adjustments of this set screw ofttimes indents or nmt-ilates the shaft, so that it is quite diiiicult to obtain the fine adjustment of parts desirable in devices of this character. By means, however` of the construction just described, it will be seen that the distortion of the metal of the sleeve serves to frictioinllly clamp the parts together'. there being no danger thereby of mutilating the shaft.

This construction has the further advantage that while the cont-act arm and its operating shaft 19 may be fastened together suilicientljY firm for the usual operative purposes, such relative movement between the shaft and the contact arm can be had wit-hout loosening the clamping screw 24, as will permit initial adjustment, so that for instance the indicator arrow 25 can be. caused to register exactly with the Zero position of the device 2G. This adjustment can be readily effected by forcing the shaft to rotative move.- ment against the stress of the clamping means while the contact arm 6 is in engagement with either of the bindingposts 7 or 10.

In Figure of the drawings I have provided a slightly modified construction as to one feature of my invention. In this tigure the clamping screw 24, it will be noted, passes through an aperture formed in one otl tl'ietlattcncd faces 14 or 15 of the sleeve 9, and directly engages with the operating shaft 19. In this modification the clamping screw 24; locks the operative parts together through direct engagement with the shaft` and also prevent-s a. retrograde movement of the n ut 21 upon the threaded portion 13 of the sleeve 9.r

It will accordingly be seen that I have provided a. construction well adapted to attain, lamong others, all the ends and objects above pointed out, in a very simple manner. rl `he device is readily assembled, is not easily distorted, andrprovides for a very accurate adjustment of parts.

As many changes could be made in this construction without departing from the scope of the following claims, it is intended that all matter` contained in the above description or lshown in the accompanying drawings, .shall be interpreted as illustrative only and not in a limiting sense. i

Ilaiing thus described,v my invent-ion what I claim as new and desire to secure bv LettcrsPatentis: 'i 'A 1 A device of the class described, in combinatiom4 a., res istance unit. a contact arm izlrlptcd to` be moved thereover, a mounting a resistance unit carried thereby, .a contact arm having a contact point adapted to travcrse said resistance unit, a sleeve extending through said block, said sleeve beingv threaded at `its outer end and provided with one or more flattened surfaces adjacent the screw threaded part thereof, said Contact arm being mounted upon said sleeve in non-rotatable relation therewith, a nut threaded upon said sleeve, and a. clamping screw extending through said nut, adapted to engage a fiattened portion thereof, and cause. the later to impinge against said shaft, so that said sleeve and said shaft are held frictionally in operative relation.

3. In a device of the class described, in combination, a block of insulating material, a. resistance unit carried thereby, the contact arm having a. contact point adapted to traverse said resistance unit, a sleeve extending through said block, said sleeve at its outer end being provided with a threaded portion and with one or more flat faces, said contact arm being mounted upon said sleeve in nonrotatable relation therewith, a shaft provided with an operating handle extending through said sleeve, a nut threaded upon said sleeve, adapted to clamp and' hold said contactl arm in position thereon, and a clamping screw extending` through said nut, adapted toengage a flat face on the sleeve, whereby said sleeve and said shaft are clamped in operative position. f i

4. In a device of the class described, in combination, a. block of insulating material, a resistance unit carried thereby, a sleeve extending through said block, a lpair of binding posts, one of which is connected with the. resistance unit, and the otherv with said sleeve, said sleeve at its VOuter end being providedwith a screw threaded part, and with one or more flat faces, a. contact arm mounted upon said sleeve and having a contact point adapted to traverse said resistance unit, a shaft extending through said sleeve, and being provided withl an operating knob or handle, a nut threaded upon said sleeve. and meansfextcnding through said nutadapted to hold said sleeve and said shaftin operative relation.

In testimony whereof. I alix my signature.

DAVID WALI). 

